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https://issues.apache.org/jira/browse/LOG4J2-1518?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15429543#comment-15429543
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Remko Popma commented on LOG4J2-1518:
-------------------------------------
Leon, I finally took a closer look at this and I see now that this is a Log4j2
issue, not a Disruptor issue.
The
[DefaultAsyncQueueFullPolicy|https://github.com/apache/logging-log4j2/blob/d00c38dddf6a3c90a29c14a73ba1f9e56bbbf0b9/log4j-core/src/main/java/org/apache/logging/log4j/core/async/DefaultAsyncQueueFullPolicy.java]
assumes that the {{toString}} method is only invoked from the background
thread. Some changes in log4j-2.6 mean that this is no longer the case.
One way to fix this is to let DefaultAsyncQueueFullPolicy always send the event
directly to the appender ({{return EventRoute.SYNCHRONOUS}}) unconditionally
when the queue is full.
You don't need to wait for the next log4j2 release to address this. You can
provide a custom policy like the below and configure log4j to use it by
specifying system property
{{-Dlog4j2.AsyncQueueFullPolicy=com.mypackage.MyQueueFullPolicy}}.
{code}
package com.mypackage;
public class MyQueueFullPolicy implements AsyncQueueFullPolicy {
@Override
public EventRoute getRoute(final long backgroundThreadId, final Level
level) {
return EventRoute.SYNCHRONOUS;
}
}
{code}
> Deadlock when using pure async and toString logs another message
> ----------------------------------------------------------------
>
> Key: LOG4J2-1518
> URL: https://issues.apache.org/jira/browse/LOG4J2-1518
> Project: Log4j 2
> Issue Type: Bug
> Affects Versions: 2.6.2
> Environment: Solaris
> Reporter: Leon Finker
> Assignee: Remko Popma
> Fix For: 2.7
>
> Attachments: 10511.jstack, async_deadlock.txt
>
>
> Hi,
> It looks like this was reported before in: LOG4J2-471
> We've encountered similar issue with one of the libraries where it's toString
> was indirectly also logging. This caused a deadlock when RingBuffer was full.
> Please see attached stack snippet.
> According to the following docs, it's possible to set sync policy to
> synchronously log the event if buffer is full. I don't see it documented.
> What's the policy option?
> https://issues.apache.org/jira/plugins/servlet/mobile#issue/LOG4J2-1080
> https://logging.apache.org/log4j/2.x/log4j-core/apidocs/org/apache/logging/log4j/core/async/AsyncQueueFullPolicyFactory.html
> Thank you
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